This invention relates to a power transmission device of a four wheel drive vehicle in which the front and rear wheels are simultateously driven.
Conventionally, there is known a saddle-type four wheel drive vehicle called "buggy car" as shown in FIGS. 1 and 2. This saddle-type four wheel drive vehicle is disclosed in Japanese Laid-open Patent Publication No. 59(1984)-120504.
In such a four wheel drive vehicle as discussed above, a drive sprocket 02 for driving rear wheels rigidly mounted on a rear wheel output shaft 01 and a drive sprocket 04 for driving front wheels rigidly mounted on a front wheel output shaft 03 are disposed opposite with respect to each other. And, the rear wheel output shaft 01 is connected to the front wheel output shaft 03 through a chain 06 within a crank case.
The problems involved in the aforementioned conventional vehicle are that since the front wheel output shaft 03 is disposed within the crank case 05 and the chain 06 for connecting the rear wheel output shaft 01 and the front wheel output shaft 03 are disposed within the crank case 05, an engine for the use of a conventional motorcycle cannot be commonly used, and a new engine is required. Thus, there cannot be expected a cost down as a result of mass production, and a large size of the engine is unavoidable.
The present invention was accomplished in view of the above problems.